Of the conventional alignment adjustments and corrections normally required for the steerable wheels of a vehicle, other than the universally provided toe-in adjustment, camber adjustment is generally considered to be the most important consideration. Camber involves the relationship of the plane of a wheel to the supporting surface, with perpendicular defined as zero camber, and a tilt of the upper wheel towards the opposite steerable wheel being defined as negative camber measured in degrees of tilt from perpendicular. Since the wheel normally is supported by a relatively wide tire "footprint" on the road, camber misalignment can cause an inner or outer edge of the tire to serve as the entire support of the vehicle at such wheel. Wide, high flotation tires, as are commonly used on four-wheel drive vehicles, amplify the problem.
Rigid axle vehicles, and particularly rigid axle four-wheel drive having steering knuckles and stub king pins are not designed with means for camber adjustment. However, despite the robust nature of such axles, the heavy use to which the axles are often put often result in camber misalignment.
Apparently, other than bending the axle, two concepts are known for correcting camber in split king pin solid axle four-wheel drive designs. The first involves the insertion of shim members between the spindle knuckle and spindle to vary the angle of the spindle, and accordingly the wheel camber. An example of this design is to be found in U.S. Pat. No. 4,037,680 issued to Clinton E. Grove. It should be noted that the Patent illustration is of a ball joint design dissimilar from that to which the instant invention pertains. While the Grove concept is applicable to split king pin designs, it is not useful with the now near standard disk brake since the disk hat is supported to the hub journalled on the spindle while the calipers are mounted on the spindle knuckle. Thus, if the spindle angle is varied relative to the spindle knuckle, the disk will not be true to the caliper orientation. In addition, removal of the spindle from the spindle knuckle involves a very significant effort.
Another available device uses a cam plate mounted in place of the Grove shim. By rotating the cam plate, various camber settings may be obtained without removal of the spindle. This second approach suffers the same drawbacks as does that of Grove with regard to disk brakes and initial installation.